Study of the frequency of the A gamma T chain of human fetal hemoglobin (in which threonine replaces isoleucine at position 75) will be continued and probably completed during the coming year. Further ramifications of the nature of fetal hemoglobin in baboons after induction by hypoxia or phenylhydrazine will be investigated in collaboration with Dr. Joseph DeSimone of the University of Illinois College of Medicine. High performance liquid chromatographic methods will be expanded in their application to separation of peptides, identification of abnormal hemoglobins, and separation of globin chains.